1. Field of the Invention
The present invention is directed to micromachines for use in optical systems, and more specifically, to silicon micromachined optical attenuators and switches for a plurality of light beams propagating along a respective plurality of beam paths.
2. Description of the Related Art
Micro-electro-mechanical systems (MEMS) are physically small systems with both electrical and mechanical components, and with dimensions on the order of microns. To achieve the small dimensions of the various components, MEMS are typically fabricated using techniques which were developed in part for integrated circuit fabrication. MEMS-based devices are found in an increasing number of applications, such as inkjet-printer cartridges, accelerometers that deploy car airbags, and other sensors and actuators. MEMS has developed into a growth industry with an estimated yearly market of tens of billions of dollars. In addition, MEMS-based optical systems, such as optical attenuators and switches, are becoming increasingly important in the field of telecommunications and computer networks.
A variable optical attenuator (VOA) is a device which can adjust the optical signal power passing through an optical fiber transmission circuit, such as dense wavelength-division multiplexing (DWDM) systems. Because the amount of light passing through an optical fiber depends on the wavelength of the light, VOAs are often needed to ensure power equalization of the individual wavelengths by adjusting the intensity for each wavelength. VOAs used in fiber optic communications system may use absorptive or reflective techniques to controllably adjust the transmitted power.
An optical switch is a device which can selectively switch optical signals from one optical circuit to another, and are typically used in optical systems such as optical add/drop multiplexers (OADMs). Various technologies can be used in optical switches, including, but not limited to, physically shifting an optical fiber to drive one or more alternative fibers, physically moving a reflective element, electro-optic effects, or magneto-optic effects.
MEMS technology has been identified as being able to satisfy the requirements of optical systems in the telecommunications and computer networking fields. These requirements include multi-channel operation in a dense package, high reliability, sufficiently fast operation, and inexpensive fabrication techniques.
According to one aspect of the present invention, an apparatus for at least partially intercepting a plurality of light beams propagating along a respective plurality of beam paths comprises a single crystal silicon substrate comprising a substrate surface with a surface normal direction. The apparatus further comprises an array comprising a plurality of modules. Each of the modules comprises a reflector comprising single crystal silicon and a reflector surface lying in a reflector plane substantially perpendicular to the substrate surface. Each module further comprises a reflector support which mounts the reflector to move substantially within the reflector plane with a displacement component along the surface normal direction of the substrate surface. Each module further comprises a reflector driver responsive to electrical current to selectively move the reflector between a first position in which the reflector intercepts at least a portion of one of the beam paths and a second position in which the reflector does not intercept the portion of one of the beam paths. At least a portion of the reflector driver is mounted to the reflector support and is conductive to electrical current, such that the reflector moves to the first position when electrical current flows therethrough and moves to the second position when electrical current flow ceases, whereby the movement of the reflectors is individually addressable.
According to another aspect of the present invention, a module for at least partially intercepting a light beam propagating along a beam path comprises a reflector comprising single crystal silicon, with the reflector lying substantially in a reflector plane. The module further comprises a reflector support which mounts the reflector. The module further comprises a reflector driver responsive to electrical current to selectively move the reflector along a curved path lying substantially in the reflector plane. The reflector is movable between a first position in which the reflector intercepts at least a portion of the beam path and a second position in which the reflector does not intercept the portion of the beam path. At least a portion of the reflector driver is mounted to the reflector support and is conductive to electrical current, such that the reflector moves to the first position when electrical current flows therethrough and moves to the second position when electrical current flow ceases.
According to another aspect of the present invention, a module for at least partially intercepting a light beam propagating along a beam path comprises a reflector comprising single crystal silicon, with the reflector lying substantially in a reflector plane. The module further comprises a reflector support which mounts the reflector. The module further comprises a reflector driver responsive to electrical current to selectively rotate the reflector about an axis substantially perpendicular to the reflector plane. The reflector is movable between a first position in which the reflector intercepts at least a portion of the beam path and a second position in which the reflector does not intercept the portion of the beam path. At least a portion of the reflector driver is mounted to the reflector support and is conductive to electrical current, such that the reflector moves to the first position when electrical current flows therethrough and moves to the second position when electrical current flow ceases.
According to another aspect of the present invention, a module for at least partially intercepting a light beam propagating along a beam path comprises a reflector comprising single crystal silicon, with the reflector lying substantially in a reflector plane. The module further comprises a reflector support which mounts the reflector. The module further comprises a reflector driver which receives and is responsive to an electrical signal to selectively rotate the reflector about an axis substantially perpendicular to the reflector plane. The reflector is movable between a first position in which the reflector intercepts at least a portion of the beam path and a second position in which the reflector does not intercept the portion of the beam path. At least a portion of the reflector driver is mounted to the reflector support and is conductive to electrical current, such that the reflector moves to the first position when the electrical signal is received and moves to the second position when the electrical signal is not received.
According to another aspect of the present invention, a module for at least partially intercepting a light beam propagating along a beam path comprises a reflector comprising single crystal silicon, with the reflector lying substantially in a reflector plane. The module further comprises a reflector support which mounts the reflector. The module further comprises a reflector driver responsive to electrical current to selectively rotate the reflector about an axis substantially perpendicular to the reflector plane. The reflector is movable between a first position in which the reflector intercepts at least a portion of the beam path and a second position in which the reflector does not intercept the portion of the beam path. At least a portion of the reflector driver is mounted to the reflector support and is conductive to electrical current, such that the reflector moves to the second position when electrical current flows therethrough and moves to the first position when electrical current flow ceases.
According to another aspect of the present invention, a module for at least partially intercepting a light beam propagating along a beam path comprises a reflector comprising single crystal silicon, with the reflector lying substantially in a reflector plane. The module further comprises a reflector support which mounts the reflector. The module further comprises a reflector driver which receives and is responsive to an electrical signal to selectively rotate the reflector about an axis substantially perpendicular to the reflector plane. The reflector is movable between a first position in which the reflector intercepts at least a portion of the beam path and a second position in which the reflector does not intercept the portion of the beam path. At least a portion of the reflector driver is mounted to the reflector support and is conductive to electrical current, such that the reflector moves to the second position when the electrical signal is received and moves to the first position when the electrical signal is not received.
According to another aspect of the present invention, a dense array comprises a magnet generating a magnetic field which is substantially uniform across a region. The dense array further comprises a plurality of modules in proximity to the region. The plurality of modules is in a generally planar array of rows and columns, with the rows and columns being generally perpendicular to one another, whereby adjacent modules are spaced from one another by less than or equal to approximately five centimeters. Each of the modules comprises a support and a flap mechanically coupled to the support. Each module further comprises a reflector coupled to the flap in a generally perpendicular orientation from the flap, and the reflector comprises single crystal silicon. Each module further comprises an electrical conduit formed on the flap, whereby an electrical current flowing through the electrical conduit of a selected module creates a force which moves the reflector of the selected module.
According to another aspect of the present invention, an apparatus for at least partially intercepting a plurality of light beams propagating along a respective plurality of beam paths comprises an array comprising a plurality of modules. Each of the modules comprises a reflecting means for reflecting a portion of a light beam, with the reflecting means lying substantially in a plane. Each module further comprises a supporting means for mounting the reflecting means to move along a curved path lying substantially in the plane. Each module further comprises a driving means for selectively moving the reflecting means between a first position in which the reflecting means intercepts at least a portion of one of the beam paths and a second position in which the reflecting means does not intercept the portion of one of the beam paths. At least a portion of the driving means is mounted to the supporting means and is conductive to electrical current, such that the reflecting means moves to the first position when electrical current flows therethrough and moves to the second position when electrical current flow ceases, whereby the movement of the reflecting means is individually addressable.
According to another aspect of the present invention, a method of at least partially intercepting a light beam propagating along a beam path comprises providing a light beam propagating along a beam path. The method further comprises providing a reflector mounted to a movable reflector support, with the reflector lying substantially in a plane and comprising single crystal silicon. The reflector is mounted to the movable reflector support such that the reflector is movable along a curved path substantially lying in the plane. The reflector is movable between a first position in which the reflector intercepts at least a portion of the beam path and a second position in which the reflector does not intercept the portion of the beam path. The method further comprises providing an electrical conduit mounted to the reflector support. The electrical conduit is conductive to electrical current, whereby the reflector moves to the first position when electrical current flows therethrough and moves to the second position when electrical current flow ceases. The method further comprises moving the reflector from the second position to the first position by applying an electrical current through the electrical conduit, thereby at least partially intercepting the light beam propagating along the beam path.
According to another aspect of the present invention, a method of switching a light beam from propagating along a first beam path to propagating along a second beam path comprises providing a light beam propagating along a first beam path. The method further comprises providing a reflector mounted to a movable reflector support, with the reflector lying substantially in a plane and comprising single crystal silicon. The reflector is mounted to the movable reflector support such that the reflector is movable along a curved path substantially lying in the plane. The reflector is movable between a first position in which the reflector substantially completely intercepts the first beam path and a second position in which the reflector does not substantially completely intercept the first beam path. The method further comprises providing an electrical conduit mounted to the reflector support. The electrical conduit is conductive to electrical current, whereby the reflector moves to the first position when electrical current flows therethrough and moves to the second position when electrical current flow ceases. The method further comprises moving the reflector from the second position to the first position by applying an electrical current through the electrical conduit, thereby switching the light beam from propagating along the first beam path to propagating along a second beam path.